The aim of this proposal is an exploration of the molecular structure of the genome, in an attempt to elucidate mechanisms of rearrangement of sequences within the genome as related to evolution and function. The majority of the sequences in most eukaryotes may prove to be arranged in a regular alternation of repetitious with single copy sequences. That so much of the DNA is interspersed implies a structural and/or functional requirement for this arrangement. These experiments are intended to examine the function of patterns of change in gene regulation in the cell, which is closely related to the abnormal alternations in the patterns of genes activated in the cancerous cell. Methods dependent on nucleic acid reassociation will be the primary emphasis. These will include hydroxyapatite chromatography, the use of Sl nuclease, and spectrophotometric studies.